The present invention relates to a method of making a mold and, more particularly, to a method suitable for carrying out so-called "cold box process" or "S0.sub.2 process" in which molding sand containing a gas-hardenable binder is supplied into a space defined by a pattern plate and a molding flask and, after a squeezing of the molding sand, a hardening gas is supplied to penetrate the molding sand to harden the molding sand thereby to form the mold.
In general, the formation of a mold by the "cold box process" or "S0.sub.2 process" requires various devices such as a squeezing device for squeezing the molding sand, gas blowing device for blowing the hardening gas into the molding sand, clamp device for clamping a pattern plate and a molding flask firmly to prevent the escape of the hardening gas, and so forth. The sizes of these devices get larger as the size of the mold to be formed becomes greater. The increased size of the mold to be formed also requires an increased force produced by the gas pressure which in turn requires a construction which has a strength high enough to withstand the increased force.
Generally, as the size of the mold to be formed is increased beyond a certain limit, it becomes difficult to mechanically squeeze the molding sand and a considerably long time is required for the satisfactory squeezing. In some cases, it is necessary to adopt a stamping work requiring a manual labour.